Read exclusive excerpts from Rose George's The Big Necessity on Slate.
More than 15 million rural Chinese homes have been provided with "biogas": a large, oxygenless digester into which they empty their toilet pans. The organic matter ferments there and belches out a gas that can then be converted into electricity; the gas also makes stoves go. It may make us retch, but it saves Chinese women from the backbreaking labor of cutting down firewood, and they love it. Is this our future? Alas, its potential spread is limited: If you don't add ample animal feces, too, the machines don't run for long.
Is there a way to safely use shit as fertilizer instead? Some U.S. firms thought so when they began to market "biosolids"—the gunk that is left over after sewage has been treated. But in 1975 the chief of the Environmental Protection Agency's Technology Board of the Hazardous Waste Division reached a horror-film conclusion. Transforming waste into fertilizer is "the most efficient means—short of eating the sludge—of injecting toxic substances directly into the human body." Almost all European countries have now banned it.
Meanwhile, the question of where to put the sewage becomes even more urgent. Our Western system of sanitation uses vast amounts of two increasingly precious resources, energy and water. It has become a cliché to say the wars of the future will be fought over water, due to global warming and a swelling population—but it is true. When water is scarce and costly, our Western model of washing away our waste ceases to make sense. George summarizes our current methods tartly: "You take clean drinking water, throw filth into it, and then spend millions to clean it again." One cubic meter of wastewater can pollute 10 cubic meters of water—and in a warming world battling for water supplies, that will soon become a ratio we can't afford. Our method is strikingly energy-intensive, too: A sewage plant uses up to 11.5 watts of energy per head, requiring an entire coal-fired power station to run just four sewage treatment facilities.
So, we need a safe alternative to plopping and peeing into water, but where is it? George talks to environmentalists who "see a future where instead of controlling pollution after it happens, we prevent it in the first place, by some sort of source separation." This eco-sewage has two prongs. First, we have to change our toilets—and our sewers—so they have two streams: one for urine and another for excrement. Although it's counterintuitive, urine actually contaminates sewer water much more severely than feces do. If it ran into a separate system, we would slash water use by an extraordinary 80 percent. The second prong is harder to imagine. As in presewer London, we would defecate into a tank, and our shit would sit there waiting for collection.
Feces take a strange and irrational physical journey because they take a strange and irrational journey through our minds. But if we are going to deal with the coming shit crises—or solve the one killing kids in the developing world today—we need to overcome an aversion that can seem hard-wired into us by our evolution and intensified by culture. The most encouraging revelation of George's book is that even the aspects of defecating that seem eternal and unchangeable are actually recent innovations. In Japan 60 years ago, everybody squatted communally over a dry pit. Today, nobody does: In private, they use techno-toilets that wash and dry your anus while simultaneously playing music and heating the seat. (Think of it as the iToilet or Toilet 3.0.)
Toilet culture can change, and fast. Neither of my parents had a toilet in the house when they were children and thought the idea was vaguely disgusting. (Defecating? Next to the kitchen?) Another toilet-tide shift may happen in my lifetime. Will the drying up of water supplies—and a sewage system with nowhere left to spew its waste—force us to regress to earlier, dirtier worlds? Or will we begin a transition to greener options before the system breaks down and begins to spew our filth back at us?
It's a sign of how superb George's book is that I am now bubbling with questions about the future of feces. The Big Necessity belongs in a rare handful of studies that take a subject that seems fixed and familiar and taboo and makes us understand it is historically contingent and dazzlingly intriguing. Jessica Mitford did it with her classic study The American Way of Death; Michel Foucault did it with Madness and Civilization. Rose George has produced their equal: a gleaming toilet manifesto for humankind. It could end with an oddly rousing cry, borrowed from another manifesto long ago: Shitters of the world, unite! You have nothing but your diarrhea and your cholera and your dying oceans to lose.